The present invention relates to optical discs, optical disc manufacturing methods and optical disc drives. In particular, the present invention relates to an optical disc structure having a deflection-formed wobbling header part, a method for forming a wobbling header part, an optical disc drive for recording data to and reproducing data from the optical disc loaded in the drive. The present invention also relates to a stamper for manufacturing the optical disc.
A higher recording density has recently been one of the most important technical issues in the art of optical discs, and various densifications have been proposed as represented by the land/groove recording.
Devised header-part structures have conventionally been proposed, as well as a data recording part, for the higher recording density. For example, iD-photo records header (part) information onto only one side of a recording track to reduce interference in a track direction, and header information on both walls at inner and outer sides of the recording track in order to avoid malfunctions resulting from a tilt of the disc.
The header part is configured to record header information through deflection, thereby providing long, uninterrupted recording tracks. Advantageously, this may result in uninterrupted detections when a tracking signal crosses tracks.
A method of recording header information into only one side of a recording track, as in the iD-photo, uses two streaks of optical beams to form wobbling headers, exposes with these two beams offset in a radial direction, and forms separate wobbles at the exposed side surfaces. Therefore, this method necessarily requires a wide exposure track width, and thus has difficulty in increasing the track density in the radial direction.
The increased track density in the radial direction with a narrower width for each track would require such an information track structure as uses a single beam instead of two beams to increase the recording density of the optical disc. In addition, reliable header information and a stagger structure, such as iD-photo, must be maintained even for a single beam for forming the wobbling header. It is also necessary to develop an optical disc drive that manages address information differently from the conventional one in order to reduce such an optical disc to practice.